RU2583893C1 - Method of checking pipeline leak control system - Google Patents

Abstract

FIELD: test equipment.

SUBSTANCE: disclosed is a method of checking leak control of pipeline, which includes reproduction system parameters of reference measured physical quantity system simulator, comparison of reproduced parameters with specified parameters of reference simulator and generation of conclusion on serviceability of system. Parameters of reference leak simulator are set before each check operability of the system in form of values of mass flow rate and location of leakage. Calculated time and temperature modes of thermal effect on each primary temperature converter system with leak with preset reference simulator parameters. Method includes applying thermal action on each primary temperature converter with calculated time and temperature modes. Registering reproduced system parameters of reference simulator. Comparing with specified parameters of reference leak simulator and considered to be system operable if said parameters within allowable standardised errors.

EFFECT: high reliability and accuracy of diagnosis.

1 cl, 2 tbl

Description

The invention relates to the diagnosis of the technical condition of complex process control systems and can be used to verify the operability of a pipeline leak control system, in particular pipelines of nuclear power plants with a water coolant.

A technical solution is known, considered in the patent of the Russian Federation for the invention No. 2184369 "Device for measuring air humidity", from the description of which there is a known method of checking its performance. The essence of the method is to remotely disconnect the elements of primary converters that are sensitive to measured physical quantities from the inputs of spatially remote amplifiers-converters, connect reference simulators of measured physical quantities to them and compare the readings of the measuring channels with connected reference simulators with the parameters of the reference simulators themselves.

The disadvantage of this method is that it does not control the technical condition of the sensitive elements of the primary transducer, which is operated under the influence of destructive factors.

The closest in technical essence to the claimed technical solution is the method disclosed in the preprint S. Morozov, S. N. Kovtun, P. A. Dvrnikov and others. Moisture control system for a leak (CKTV) of a water coolant. Preprint FEI-3080. Obninsk, 2006, 20 p.

The essence of the method consists in periodically remotely disconnecting from the inputs of amplifiers-converters channels for measuring relative humidity and air temperature, sensitive to the measured physical quantities of elements, a capacitive sensor of relative humidity and a resistive sensor of air temperature, and remotely connecting reference simulators of measured physical quantities, a reference instead a capacitor and a reference resistor, recording the readings of the measuring channels with this connected bosom simulators and comparing the reproduced parameters of the reference simulators with the parameters of the reference simulators themselves. The described method allows you to control communication lines between the primary converters and spatially remote amplifiers-converters of the measuring channels and the safety of the characteristics of amplifiers-converters at the control point specified by the parameters of the simulators of physical quantities.

A disadvantage of the known technical solution is the lack of comprehensive control by the system of the operability of the sensitive elements of the primary transducers and the electrical characteristics of the measuring channels, as well as the lack of a comprehensive check of the algorithm for determining the location and mass flow rate of the leak according to the readings of the primary transducers involved in the controlled section of the pipeline.

The objective of the invention is to remedy these disadvantages, namely, providing comprehensive control by the system of the operability of the sensitive elements of the primary transducers and the electrical characteristics of the measuring channels, as well as providing a comprehensive verification of the algorithm for determining the location and mass flow rate of the leak.

EFFECT: expanding the functionality of a method for verifying the operability of a pipeline leak control system.

In order to eliminate the indicated drawbacks in the method of verifying the operability of the pipeline leak monitoring system, which includes reproducing by the system the parameters of the reference simulator measured by the system of physical quantities, comparing the reproduced parameters with the specified parameters of the reference simulator and drawing a conclusion about the system’s operability, it is proposed:

- Before each check of the system’s operability, set the parameters of the reference leak simulator in the form of mass flow rate and leak location;

- to calculate the time and temperature conditions of the thermal effect on each primary temperature transducer of the system during a leak with a given reference simulator of mass flow and the location of the leak;

- conduct a thermal effect on each primary temperature converter in compliance with the calculated time and temperature conditions and register the parameters of the reference simulator reproduced by the system;

- compare the specified parameters of the simulator;

- recognize the performance of the system provided that the parameters of the reference leak simulator reproduced by the system coincide within the limits of permissible normalized errors.

The essence of the method is as follows.

A method for verifying the operability of a pipeline leak monitoring system includes reproducing a system of parameters of a reference simulator as measured by the system of physical quantities, comparing reproduced parameters with predetermined parameters of a reference simulator, and drawing a conclusion about the system's operability.

The parameters of the reference leak simulator are set before each test of the system's operability in the form of mass flow rates and leak location.

The time and temperature regimes of the thermal effect on each primary temperature transducer of the system are calculated during a leak with the parameters specified by the reference simulator.

Conduct a thermal effect on each primary temperature transducer in compliance with the calculated time and temperature conditions.

The parameters of the reference simulator reproduced by the system are recorded, they are compared with the specified parameters of the reference leak simulator, and the system is recognized to be operable provided that the specified parameters coincide within the limits of permissible normalized errors.

The method is intended to check a pipeline leak control system, in which the effect of a temperature increase recorded by three thermoelectric converters (TEC) installed at known distances (X ₁ , X ₂ and X ₃ ) along the length of the pipeline section being monitored is used as a physical leak sign. TECs are installed in pipes, the lower ends of which are articulated with the space of the pipeline formed by the gap between the outer diameter of the pipeline and the inner diameter of the insulation. The system constantly measures the air temperature at the TEC installation sites. In the presence of a pipeline leak, the generated vapor, due to excess pressure, spreads evenly from the leak (X _T ) to both sides along the pipeline insulation space, while some of the steam through the nozzles enters the environment, which leads to an increase in the air temperature in the nozzles, which is recorded TEP. Since TECs are located at different distances from the leak, the time points for increasing the readings of the corresponding measuring channels will be different and dependent on the magnitude (flow) of the leak. The moments of time when the measuring channels reach the temperature settings are recorded and used as input in the algorithm for calculating leak parameters — flow rate and coordinates of the leak location.

To verify the health of the described system, you must perform the following steps:

1. Set the parameters of the reference leak: the reference value of the leak rate G _et and the reference coordinate of the leak site X _et , whose values are within the measurement ranges of the flow system and the coordinates of the leak location.

2. Using the specified parameters of the reference leak, calculate the time and temperature regimes of the thermal effect on all TECs, for which determine:

прохождения парогазового фронта (ПГФ) вдоль подизоляционного пространства по формуле- average speed $$\overline{W}$$

passage of a gas-vapor front (PGF) along the insulating space according to the formula

where ν is the specific volume of superheated gas at a temperature of the insulating space; S - sectional area of the insulating space of the pipeline;

- times t ₁ , t ₂ , t _{3 of the} passage of PHF distances from a given reference leak point (X _floor ) to the installation sites of the primary transducers (X ₁ , X ₂ and X ₃ ), which is equivalent to the times from the moment of the leak beginning to the moments of heat exposure primary converters, according to the formulas:

if

or by the formulas:

if

- the time of the artificial thermal effect on the thermoelectrodes of the TEC (t _etc. ) according to the formula

the heating current of thermoelectrodes TEP according to the formula

where ΔT is the temperature setpoint value, defined as the excess of temperature over the background; k is the coefficient of proportionality between the rate of increase of temperature readings by measuring channels and the heating current of thermoelectrodes TEC.

3. Record the temperature readings T _f1 , T _f2 and T _{f3 by} measuring channels in the absence of leakage (background temperatures).

4. At the same time, disconnect all TECs from the inputs of the amplifier-converters of the measuring channels and, after times t ₁ , t ₂ , t _3, connect the corresponding TECs to the current source (heat source).

5. After the time of artificial thermal influence on the TEC (t _etc. ) _expires, at the same time disconnect them from the current source and connect to the inputs of the amplifier-converters of the measuring channels, record the temperature readings, the values of which are described by the formulas:

where i = 1,2,3.

, $$t_2^{\text{'}}$$

, $$t_3^{\text{'}}$$

превышения каждым измерительным каналом уставки по температуре ΔT по формуле6. Calculate time points $$t_{\mathrm{one}}^{\text{'}\text{'}}$$

, $$t_2^{\text{'}\text{'}}$$

, $$t_3^{\text{'}\text{'}}$$

each measuring channel exceeds the temperature setting ΔT according to the formula

и $$G_{эт}^{\text{'}}$$

по соответствующим формулам7. Determine the parameters of the reference leakage reproduced by the system $$X_{\mathrm{uh}t}^{\text{'}\text{'}}$$

and $$G_{\mathrm{uh}t}^{\text{'}\text{'}}$$

according to the corresponding formulas

at

at

8. Compare the reproduced leak parameters X 'and G' with the specified reference parameters and verify the conditions

where ΔG and ΔX are the limits of permissible normalized absolute errors, respectively, of the leak rate and the coordinates of the leak site.

9. Accept that if conditions (1) are fulfilled, the system with the TEC installed in the controlled area is operational.

To check the leakage control system for pipelines of nuclear power plants with a water coolant as acceptable normalized errors in expression (1), use the recommended limits for determining the flow rate and coordinates of the leak, respectively ± 50%, ± 2 m along the length of the monitored pipeline section.

Thus, the method of verifying the operability of the pipeline leak control system involves sensitive elements of primary transducers and the algorithm of the system’s operation for determining the flow rate and the location of the leak, and also makes it possible to control the operability of the system in all ranges of its controlled flow rates and the coordinates of the leak locations by setting the corresponding parameters of the reference leak during periodic checks of its performance.

We show the efficiency of the method on a specific numerical example.

Table 1 shows the initial data necessary for the system to implement the algorithm for determining the flow rate and the coordinates of the leak and conducting a check of its performance.

Table 2 shows the intermediate results of the calculations to verify the health of the proposed method.

An analysis of the results of the calculation of the phased implementation of the method shows that the technical capabilities of the system provide both temporary and temperature parameters of artificial heat exposure on the primary transducers in the entire measurement range, and the coincidence of the specified parameters of the reference leak with the reproduced parameters demonstrate the efficiency of the method.

For the technical implementation of the method, it is necessary to supplement the technical means of the system with a source of thermal influence on the TEC in the form of a current source with the ability to programmatically control the current value and a program-controlled switch necessary to remotely disconnect the TEC from the inputs of the measuring channels and connect them to the heat source in a given time mode .

The industrial applicability of the method is justified by the fundamental possibility of using the method in temperature leakage control systems, in particular, pipelines of the primary circuit of nuclear power plants with a water coolant.

Claims (1)

A method for verifying the operability of a pipeline leak control system, including reproducing a system of parameters of a reference simulator as measured by a system of physical quantities, comparing reproduced parameters with the specified parameters of a reference simulator, and drawing a conclusion about the system’s operability, characterized in that the parameters of a reference leak simulator are set before each system operability check in the form mass flow rate and location of the leak, calculate the time and temperature conditions of those total impact on each primary temperature transducer of the system during a leak with the parameters specified by the reference simulator, conduct thermal effects on each primary temperature transducer in compliance with the calculated time and temperature conditions, record the parameters of the reference simulator reproduced by the system, compare them with the specified parameters of the reference leak simulator and recognize the system workable provided that the specified parameters coincide within the allowable normalized error ostey.